text: #!/usr/bin/env python
  # Licensed to Cloudera, Inc. under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  Cloudera, Inc. licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import re
  
  from django.contrib.auth.models import User
  from django.core.validators import RegexValidator
  
  from desktop.lib.django_util import get_username_re_rule
  
  
  def monkey_patch_username_validator():
    """
    In 1.6, the `User.username` field gained some validation rules to check that
    it conformed to a particular regex. Unfortunately we use to support a more
    liberal username scheme. The proper solution would be to use our own custom
    user model, but that touches a lot of code. It's easier if we just modify the
    regular expression inside the username validator.
    """
  
    username = User._meta.get_field("username")
  
    regex = re.compile('^%s$' % get_username_re_rule())
  
    for validator in username.validators:
      if isinstance(validator, RegexValidator):
        validator.regex = regex
  
  
  monkey_patch_username_validator()
  